Alarm action Shutdown turns off the machine immediately

Hi,

what does Alarm action "Shut down" in Power Options is supposed to do ? I
have connected an APC UPS via USB and I'd like to perform normal shutdown
when the battery level reaches 30%. I thought that the alarm action "Shut
down" does the task but it turns off the machine immediately instead of
closing all applications and perform standard shutdown operation. There is no
record in Event Log indicating normal shutdown. Do I have to use "Run a
program" option with a shutdown.exe application ?

Moreover I'd like to perform the shutdown as Limited User. Currently I used
those registry permission hacks to enable the Power Options Properites
dialog. I have Windows XP SP3 + all updates.

Thanks.